The present invention relates to a gas blowing nozzle of a charged particle beam apparatus for blowing an assist gas or a raw material gas to a sample face on the occasion of a beam assist etching or a beam assist deposition which uses a focussed ion beam or an electron beam, and a charged particle apparatus as well as a working method.
As a defect correction of a photomask used in a manufacturing process of LSI and a technique for creation-working a fine structure such as micromachine, there have been known the beam assist etching and the beam assist deposition (FIB-CVD) by a focussed ion beam (FIB) apparatus.
As shown in FIG. 4, as a general constitution, the FIB apparatus possesses an ion optical system for focussing an ion beam IB, which contains an ion source 14, a condenser lens 20, a beam blanker 21, an aligner 22, a stop 23, a sting meter/aligner 24, an objective lens 25 and the like, a deflector 16 for deflecting the ion beam IB a gas gun 12, a secondary charged particle detector 17, and a sample stage 13 with a drive mechanism (not shown) for mounting a sample P. A working is performed by making a surface region P1 of the sample P to which the ion beam IB is irradiated into a predetermined gas atmosphere state by blowing a gas from a nozzle of the gas gun 12.
In the beam assist etching of the former, if the ion beam is irradiated to the sample face while blowing a halogen-based gas from the gas gun, an etching accompanying a chemical reaction between the sample and the gas is performed by the ion beam irradiation in the gas atmosphere. This etching is generally rapid in its etching speed by the fact that a substance generated by the reaction vaporizes, and has a characteristic that a residue like in a sputter etching does not remain.
Further, the beam assist deposition of the latter is one in which the ion beam is irradiated to the sample face under a state that a raw material gas has been jetted from the gas gun, and the raw material gas causes a decomposition reaction by being subjected to the beam irradiation, thereby forming a structure by depositing a product onto the sample face. There are known one in which a diamond-like carbon (DLC) is deposited to the sample face by using aromatic hydrocarbon such as phenanthrene:C14H10 as the raw material, one in which tungsten is deposited to the sample face by using hexacarbonyltungsten:W (CO6) for the raw material gas, and the like.
Since these reactions locally occur in a beam irradiation position, a fine etching working and a formation of the fine structure are possible by controlling the beam position, and they are used in the defect correction of the photomask used in an LSI manufacture and the formation of the micromachine or the like.
It is known that the gas nozzle of the gas gun used on these occasions is necessary to be disposed at a very short distance of 500 μm or less from the sample face in order to ensure a necessary gas concentration in a reaction region and, unless a concentration distribution is symmetrical with the beam irradiation position being made a center, the etching and the structure formation become unbalanced.
In this regard, as shown in FIG. 3A, it is known that in the gas concentration distribution on the sample surface under gas injection from a single gas nozzle 2a, the peak of the gas concentration is located around and right under the center of the end portion of the nozzle.
The conventional position of the ion beam irradiation is located away from the peak of the gas concentration distribution because the ion beam is blocked by the gas nozzle as shown in FIG. 3A. This results in a problem that the gas concentration distribution becomes asymmetrical with respect to the beam irradiation position and the symmetry of beam assist processing can not be secured.
As a method of solving this problem that the ion beam 5 does not reach the peak position of the gas concentration distribution, for example in Patent Document 1 (JP-A-2003-13226 Gazette (paragraph numbers 0037-0038, FIG. 3)), there is adopted the fact that a peak of the gas concentration is made in a center part of plural nozzle tip parts by using plural gas nozzles to thereby supplement mutual distributions. By doing like this, it is adapted so as to capable of sighting the beam center at the peak position of the gas concentration.
That is, as shown in FIG. 3B, in a case where 2 gas nozzles 2a are disposed so as to be opposed, the concentration distributions, shown by broken lines, of the gas jetted from the respective gas nozzles 2a are synthesized, and the gas distribution resultantly formed becomes such a normal distribution as shown by a solid line. In this case, it is possible to bring the peak position of the gas concentration to an intermediate position of both the nozzle 2a tip parts, and the ion beam 5 irradiation to the peak position becomes possible. So that, the symmetry of processing can be secured.
Further, there is known a gas delivery system (for example, refer to Patent Document 2 (JP-T-2000-512809 Gazette (FIG. 2) (the term “JP-T” as used herein means a published Japanese translation of a PCT patent application)) for a particle beam working, which can vertically deliver a fluid reactant (gas) to a work (base plate) in a particle beam (beam) irradiation position by utilizing a concentration device (inverted funnel tube in a vertical direction) provided in a tip of a fluid delivery conduit (gas nozzle).
According to this gas delivery system for the particle beam working, it is adapted such that, since the gas and the beam reach the work while passing through an inside of a passage formed in the same concentration device, the beam center can be sighted at the peak position of the gas concentration.
However, in the conventional one described in the above Patent Document 1 or 2 etc., there have been such problems as mentioned below.
That is, in a case where a nozzle disposition form described in the above Patent Document 1 has been adopted, in an FIB working there occasionally occurs a necessity to perform the working by tilting the sample face, so that there arises a new disadvantage that, when it is attempted to implement the working, either of the nozzle tip parts butts against the sample face because a distance between the nozzle tip and the sample face is very short.
Further, similarly, as described in the above Patent Document 2, since it is necessary to locate the concentration device having the complicated shape near the sample face, there has arisen a problem that, when the sample face has been tilted, the concentration device interferes with the sample face. For this reason, it has been impossible to perform the beam assist deposition or the beam assist etching under a state that the sample has been slanted.
Further, there has been a fear that a detection efficiency of secondary electrons decreases because the concentration device influences. For this reason, at a small electric current time such as nano-working, it has been difficult to perform a sample observation etc. utilizing the secondary electrons.
Additionally, since the concentration device is long in a longitudinal direction vertical to the sample face, there has been a fear that, in a case where a gas whose concentration is high has been used, the beam is scattered and thus an influence is exerted upon a working accuracy.
Incidentally, in the above explanations, although the deposition working has been made an example, also in a case of the beam assist etching it becomes a similar phenomenon and thus there arises a problem that an asymmetrical property of the etching working.
This invention is one made in view of the above problems of the prior art, and its object is to provide a gas blowing nozzle of a charged particle beam apparatus, which makes it possible, on the occasion of performing the beam assist deposition or the beam assist etching by using the charged particle beam apparatus, to perform a beam irradiation to the peak position of the gas concentration and can ensure the symmetrical property of that working without exerting an influence upon the drive of a sample stage and which exerts no influence upon the secondary electron detection efficiency and the working accuracy, and a charged particle beam apparatus as well as a working method.